The Gundam GP03 is based on Bandai MG kit in combination of a Korea Resin Kit.  The kit gives the GP03 a boarder shoulder, massive body armor, and a detailed back wing.  The beam gun is also thicker than the original.

To compare our modified kit to a standard MG kit, you can take a look at the work from Dalong.net.  Here is the link to their GP03:

http://www.dalong.net/review/mg/m38/th/s_m38_n02.jpg